Ethanol is a neuroteratogen and alcohol consumption during pregnancy causes Fetal Alcohol Spectrum Disorders (FASD). FASD are currently the leading cause of mental retardation in North America. The most devastating effect of developmental exposure to ethanol is the loss of CNS neurons which underlie many behavioral deficits observed in FASD. We demonstrated that ethanol caused both oxidative stress and endoplasmic reticulum (ER) stress in the developing brain. We showed that ethanol induced the expression of monocyte chemoattractant protein-1 (MCP-1) and a specific ER stress-inducible protein, mesencephalic astrocyte-derived neurotrophic factor (MANF). Our studies suggested that both MCP-1 and MANF were involved in ethanol-induced ER stress and neuron death. The central hypothesis for this proposal is that ethanol-induced neurodegeneration in the developing brain is mediated by the interplay of oxidative stress and ER stress. Three corollary hypotheses will be tested: 1) ethanol-mediated oxidative stress causes an early neuron death; the second phase of neuron death is mainly mediated by ethanol-induced ER stress or a combined action of both oxidative stress and ER stress; 2) the oxidative stress-induced neuron death is mainly regulated by the mitochondrial intrinsic apoptotic pathway; while the ER stress-induced neuron death is mediated by the GSK3?/calpain/caspase7/12 pathway; 3) activation of MCP-1 mediated signaling potentiates ethanol-induced ER stress and promotes an ER stress-initiated apoptotic program in neurons; contrarily, MANF is a neuroprotective protein which alleviates ethanol-induced ER stress and neuron death. We propose three specific aims to test these hypotheses. Specific Aim 1 will test the hypothesis that ethanol-induced neuron death is caused by the interplay of oxidative stress and ER stress in vitro. Specific Aim 2 will determine the role of MCP-1 signaling and MANF in ethanol-induced ER stress and neuron death in the developing brain. Specific Aim 3 will determine whether simultaneous inhibition of oxidative stress and ER stress offers maximal protection and improves behavioral deficits in mice. As a unit, this proposal will systematically investigate the interplay of oxidative stress and ER stress and assess their contribution to ethanol-induced neuron death. This study will therefore not only provide novel insight into the mechanisms of ethanol-induced damage to the developing CNS but also identify specific targets for developing effective therapeutic strategies.